[Reza_th]

Dear friends
I wrote a UDF for one of my walls and this UDF will calculate the heat flux based on my simulation condition.

The code compiled corectly in fluent by when I run the simulation i have the error of Error: floating point exception

can someone review my code and help me through this?


Thanks




#include "udf.h"

real T_inf_BC2 = 273.15;
real h_BC2 = -2000.0;
real h_BC3 = 10; // Typical value we used
real m_snow_initial = 0.0005; // Constant initial value for mass of snow per unit area [Kg/m^2]
real ice_density = 917; // Density of ice [kg/m³] - Typical value @ standard atmospheric pressure and 0 degrees Celsius
real Boltzmann = 5.67 * 10e-8; //[W/m²·K⁴]
real hif = 334000; // Heat of fusion of snow [J/kg]
real dt = 300; // Time step length [s]
real A = 0.009;//Aprx area of each cell [m^2]
real K = 0.1;
int cell = 1560; // Total number of cell on the surface

DEFINE_PROFILE(heat_flux_bc, thread, position)
{
real x[ND_ND];
real flux;
real time = CURRENT_TIME;
real flow_time = RP_Get_Real("flow-time");
static real m_snow_time_step = 0;
real snow_fall_rate;
real ambient_temperature;
real m_snow;
real h_snow;
real m_dot_melt;
real T_snow;
real h_BC1 = (K / h_snow * A);
static int i = 1;
int J = 0;

face_t f;
real T_wall;

FILE* file;
char line[256];

file = fopen("C:/Users/MOTOH/Desktop/file.txt", "r");
if (file == NULL)
{
Message("Error: Unable to open file.\n");
return;
}

while (fgets(line, sizeof(line), file) != NULL)
{
real file_time;
real ambient_temperature_file;
real snow_fall_rate_file;
sscanf(line, "%lf, %lf, %lf",
&file_time, &ambient_temperature_file, &snow_fall_rate_file);

ambient_temperature = ambient_temperature_file;
snow_fall_rate = snow_fall_rate_file;

if (time >= file_time)
{
break;
}
}

fclose(file);

begin_f_loop(f, thread)
{
F_CENTROID(x, f, thread);
T_wall = C_T(f, thread);

if (T_wall < 273.15)
{
if (i == 1)
{
m_snow = m_snow_initial;
h_snow = m_snow / (ice_density * A);
T_snow = ambient_temperature;
flux = (h_BC1 * (T_wall - T_snow));
m_snow_time_step = m_snow + (snow_fall_rate * dt);
}
else
{
m_snow = m_snow_time_step;
h_snow = m_snow / (ice_density * A);
T_snow = ambient_temperature;
flux = (h_BC1 * (T_wall - T_snow));
m_snow_time_step = m_snow + (snow_fall_rate * dt);
}
}
else
{
if (m_snow_time_step == 0)
{
flux = h_BC3 * (T_wall - ambient_temperature);
}
else
{
m_snow = m_snow_time_step;
h_snow = m_snow / (ice_density * A);
real q_cond_snow = (h_BC1 * (T_wall - T_snow));
flux = (h_BC2 * (T_wall - T_inf_BC2));
real q_melt = flux - q_cond_snow;
m_dot_melt = q_melt / hif;
m_snow_time_step = m_snow + ((snow_fall_rate - m_dot_melt) * dt);
}
}
if (m_snow_time_step == 0.0)
{
J++;
}
F_PROFILE(f, thread, position) = -flux;
}
end_f_loop(f, thread)

i++;

Message("Percentage of area free of snow: %.2f%%\n", (J / cell) * 100.0);

[AlexanderZ]

at least one variable is not defined

for instance
real h_BC1 = (K / h_snow * A);
h_snow is not defined

read compilation log